1. Field of the Invention
The present invention relates to an air pump and, more specifically, to an air pumping/extracting duplex pump adapted for use in an inflatable device to selectively inflate/deflate the inflatable device.
2. Description of the Related Art
When inflatable/deflating a big inflatable device, an air pump is used. A big inflatable device generally has a first one-way air valve for enabling air to pass to the inside, and a second one-way air valve for enabling air to pass to the outside. When inflating this kind of big inflatable device with an air pump, the air exhaust port of the air pump is connected to the first one-way air valve of the inflatable device. On the contrary, when deflating this kind of big inflatable device with an air pump, the air suction port of the air pump is connected to the second one-way air valve of the inflatable device. This inflatable device inflating or deflating procedure is complicated.
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a duplex pump, which is practical for use in an inflatable device to selectively inflate/deflate the inflatable device. It is another object of the present invention to provide an air pumping/extracting duplex pump, which is easy to operate. To achieve these and other objects of the present invention, the air pumping/extracting duplex pump is installed in an inflatable device having a flexible shell defining an air chamber, and adapted for selectively pumping air into/out of the air chamber of the inflatable device. The air pumping/extracting duplex pump is comprised of a first housing, a second housing, and an actuating mechanism. The first housing is fixedly fastened to the flexible shell of the inflatable device, comprising an air chamber, an air inlet and an air outlet respectively disposed in communication between the air chamber of the first housing and the air chamber of the inflatable device, a first one-way air valve installed in the air outlet for enabling air to pass from the air chamber of the first housing into the air chamber of the inflatable device, and a second one-way air valve installed in the air inlet for enabling air to pass from the air chamber of the inflatable device into the air chamber of the first housing. The second housing is fixedly fastened to the first housing and extended to the outside of the inflatable device, comprising an air chamber disposed in communication with the air chamber of the first housing, a first opening disposed in communication with the air chamber of the second housing and the atmosphere, a second opening disposed in communication with the air chamber of the second housing and the air chamber of the first housing, and an annular airflow control plate fixedly fastened to the periphery of the second opening, the annular airflow control plate having a radially inwardly protruded first stop flange and at least one radially inwardly protruded second stop flange. The actuating mechanism is mounted in the first housing and the second housing and rotatable relative to the first housing and the second housing between a first position for drawing air into the air chamber of the inflatable bed and a second position for drawing air out of the air chamber of the inflatable device. The actuating mechanism comprises an outward flange supported on the airflow control plate, a first part disposed at one side of the outward flange inside the air chamber of the first housing, and a second part disposed at an opposite side of the outward flange inside the air chamber of the second housing, the first part having an air suction hole, an air exhaust hole, and a protruded portion, the outward flange having a first air hole disposed in communication with the exhaust hole and at least one second air hole disposed in communication between the first part and the second part. When the actuating mechanism rotated to the first position, the first stop flange of the airflow control plate blocks the first air hole of the actuating mechanism, the at least one second air hole of the actuating mechanism each is opened, and the air exhaust hole of the actuating mechanism is in communication with the air outlet of the first housing for enabling outside air to be drawn into the air chamber of the inflatable device upon operation of the actuating device. When the actuating mechanism rotated to the second position, the protruded portion of the actuating mechanism opens the second one-way air valve, the air exhaust hole of the actuating mechanism is moved away from the air outlet of the first housing and blocked by the periphery of the first housing, the first air hole of the actuating mechanism is moved away from the first stop flange of the airflow control plate and opened, and the at least one second air hole is respectively blocked by the at least one stop flange of the airflow control plate, enabling air to pass from the air chamber of the inflatable device through the air inlet of the first housing, the air chamber of the first housing, the first air hole of the actuating mechanism, the air chamber of the second housing, and the first opening of the second housing to the outside of the inflatable device.